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초록

Achieving stable operation at high current densities is a critical challenge for acidic water electrolysis, where intensified bubble evolution induces concentration polarization and mechanical stress that accelerate catalyst degradation. Here, we report Mo2C nanoclusters in situ anchored onto nitrogen-doped carbon nanotubes (NCNTs) via strong Mo & horbar;C and Mo & horbar;N covalent bonds. The covalent integration, achieved through electrostatically guided self-assembly followed by carbonization, yields a porous and conductive network that combines efficient charge transport with resistance to acidic corrosion. The resulting catalyst delivers overpotentials of 256 mV at 500 mA cm-2 and 396 mV at 1000 mA cm-2 in 0.5 m H2SO4, and operates stably at 865 mA cm-2 for over 240 h. In a proton exchange membrane water electrolyzer, it sustains overall water splitting at 1000 mA cm-2 with a cell voltage of 2.03 V for more than 150 h. This hierarchical covalent design enhances conductivity, durability, and bubble management, representing a scalable strategy for next-generation electrocatalysts capable of ampere-level operation in acidic media.

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